(1) Field of the Invention
The present invention relates to a high-speed method and apparatus for taking up a bundle of filaments. More particularly, the invention relates to a method and apparatus in which a bundle of filaments is discharged in the form of coils from a rotary guide passage and coils of the bundle of filaments are accumulated in a container such as a can. The bundle of filaments is hereinafter refered to as "a filament-bundle" which means a bundle of individual filaments, such as a tow or multifilament yarn.
(2) Description of the Prior Art
In the process for preparing synthetic fibers, especially staple fibers, a number of filament-bundles produced in the spinning process are collected to form a tow which is received in a container such as a tow can. Subsequently at the drawing step, the tow is taken out of the tow can, drawn, subjected to a crimping-treatment or the like, and then cut to form staple fibers.
Recently, yarn spinning speed have been increased so as to enhance the manufacturing efficiency, until high-speed spinning at 2500 to 5000 m/min has been been tried. When a conventional method for collecting tows in tow cans, for example a nip reel method or a simple conventional coiler method, is applied to tows spun at such high speeds, it is impossible to collect the tows in tow cans in good order. Consequently, the tows become easily entangled when taken out at the subsequent step and such problems as wrapping the yarn around a roller or breakage of the yarn, cannot be avoided.
In the conventional nip reel method, since a filament-bundle such as a tow is caused to fall down into tow cans vertically, the tow sticks into layers of deposited tow at high speeds, and when the tow is taken out of the tow cans, it is entangled or entwined and cannot be removed normally in good order. On the other hand, in the conventional coiler method, as described in Japanese Utility Model Publication No. 35893/64 or Japanese Utilty Model Publication No. 20805/71, a rotating tube for guiding a bundle of fibers (called a sliver) is open at a bottom surface of a coiler wheel. If such a method is applied to accumulate the tow into a can at high running speed various disadvantages result, such as sticking of the deposited tow into layers previously deposited and formation of fluffs owing to bending of filaments at the outlet of the coiler. Furthermore, it is almost impossible to receive the coil of tow stably into the can.
In order to take up a synthetic fiber tow running at a high speed and store it in a can while overcoming the foregoing disadvantages involved in the conventional coiler apparatus, Japanese Patent Application Laid-Open Specifications No. 105413/76 and No. 133537/76 propose a method and an apparatus in which a tow running at a high-speed is sucked by a fluid ejector (air jet) and then discharged through a curved tube or tubular guide passage (tow guide tube) rotating coaxially with the ejector in the direction of the circumferential tangent, and the rotation direction of a tubular guide passage (coiler) is reversed relative to the tow discharge direction to counteract the running speed of the tow by the peripheral speed of the coiler, whereby coils of the tow can be stably formed. When such an apparatus or method is adopted, it is possible to take up a filament-bundle or tow at high speeds in the form of coils. However, the use of the apparatus in those Laid-Open Specifications still leaves certain problems to be solved.
In the first place, clogging or jamming of the guide tube is caused by entanglement of a bundle of filaments running in the guide tube. As a result of research conducted on causes of this undesirable phenomenon, the inventors of the present invention found that the main cause is that, since the guide tube having a circular section is curved, compressed air jetted from the fluid ejector and running in this guide tube swirls, and consequently, the filament-bundle also swirls as it runs in the guide tube. When modulatory waves of tension variation caused by the threading operation of the filament-bundle or tow are transmitted to the filament-bundle in the guide tube while swirling, turbulences are imparted to the swirling movement of the filament-bundle and the individual filaments thereof are caused to impinge against one another in the narrow space of the guide tube, instantaneously clogging the guide tube with entangled filaments.
In the second place, scratches, called "fluffs," are created on the individual filaments of the filament-bundle. More specifically, since the filament-bundle is prevented from running in the central portion of the guide tube because of the swirling of the compressed air and, instead, runs in rubbing contact with the inner wall of the guide tube, such scratches are created. Accordingly, the inner wall of the guide tube also extremely damaged. Furthermore, since the guide tube is curved, efforts to improve the abrasion resistance of the inner wall by a finishing treatment of the inner wall do not produce good results because it is very difficult to apply a uniform finishing treatment over the entire inner wall.
In the third place, compressed air jetted from the outlet of the guide tube together with the filament-bundle impinges against the bundle previously falling along a coil-like locus, and therefore, the coil formation of the filament-bundle is disturbed. In general, the fluid ejector imparts sufficient tension to the filament-bundle to prevent the filament-bundle from being wound on rollers at the upstream position of the passage. When the filament-bundle is taken up at a high-speed, the velocity of compressed air jetted from this fluid ejector is elevated to a subsonic level, and this speed is gradually reduced as the compressed air passes through the guide tube. However, when the compressed air is jetted from the outlet of the guide tube, its speed is still maintained at a level two to three times the running speed of the filament-bundle. Therefore, when compressed air jetted from the outlet of the guide tube impinges against previously released turns of the filament-bundle falling along a coil-like locus, the coil formation of the bundle of filaments is readily disturbed. Moreover, this compressed air jet separates individual filaments of the falling filament-bundle, resulting in a reduction of the cohesiveness of the filament-bundle.
Still further, when the thickness of the filament-bundle is small and the running speed of the filament-bundle is high, the above-mentioned disturbing effect of compressed air is enhanced. According to the conventional technique, in order to eliminate this disturbing effect, it is necessary that the diameter of formed coils should be very small, for example, 110 to about 150 mm. However, if the coil diameter is thus reduced, it is necessary to rotate the coiler wheel at an extremely high-speed. In this case, false twists are left on the filament-bundle at a rate of 2 to 3 turns per meter, and these false twists cause various troubles in the subsequent process, such as the drawing process. Also, the tow-coil falling down on the tow already deposited in the tow can has some momentum and tends to disturb the layer of the tow-coil in the can. This causes troubles when the tow is subsequently removed.